<template>
  <div class="course">
    <Header></Header>
    <div class="main">
      <!-- 筛选条件 -->
      <div class="condition">
        <ul class="cate-list">
          <li class="title">课程分类:</li>
          <li :class="filter.course_category==0 ? 'this': ''"
              @click="filter.course_category=0"
          >
            全部
          </li>
          <li v-for="item in category_list"
              :key="item.id"
              @click="filter.course_category=item.id"
              :class="filter.course_category==item.id ? 'this': ''"
          >
            {{ item.name }}
          </li>
        </ul>

        <div class="ordering">
          <ul>
            <li class="title">筛&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;选: </li>
            <li class="default"
                :class="(filter.ordering=='-id' || filter.ordering=='id')? 'this': ''"
                @click="filter.ordering=='-id' ? filter.ordering='id': filter.ordering='-id'"
            >
              默认
            </li>
            <li class="hot"
                :class="(filter.ordering=='-students' || filter.ordering=='students')? 'this': ''"
                @click="filter.ordering=='-students' ? filter.ordering='students': filter.ordering='-students'"
            >
              人气
            </li>
            <li class="price"
                :class="(filter.ordering=='-price' || filter.ordering=='price') ? 'this': ''"
                @click="filter.ordering=='-price' ? filter.ordering='price': filter.ordering='-price'"
            >
              价格
            </li>
          </ul>
          <p class="condition-result">共{{ course_total }}个课程</p>
        </div>
      </div>
      <!-- 课程列表 -->
      <div class="course-list">
        <router-link
          tag="div"
          :to="{ name: 'detail', params: { id: item.id } }"
          v-for="item in course_list"
          :key="item.id"
        >
          <div class="course-item">
            <div class="course-image">
            <img :src="item.course_img" alt="">
          </div>
            <div class="course-info">
              <h3>{{ item.name }} <span><img src="/static/image/avatar1.svg" alt="">{{ item.students }}人已加入学习</span></h3>
              <p class="teather-info">{{ item.teacher.name }} 金角大王 {{ item.teacher.title }} <span>共{{ item.lessons }}课时/更新完成</span></p>
              <ul class="lesson-list">
                <li v-for="(lesson, key) in item.lesson_list"
                    :key="lesson.id"
                >
                  <span class="lesson-title">0{{ key }} | 第{{ lesson.chapter }}节：{{ lesson.name }}</span>
                  <span class="free">免费</span>
                </li>
              </ul>
              <div class="pay-box">
                <span class="discount-type">限时免费</span>
                <span class="discount-price">￥{{ item.real_price }}元</span>
                <span class="original-price">原价：{{ item.price }}元</span>
                <span class="buy-now">立即购买</span>
              </div>
            </div>
          </div>
        </router-link>

        <div class="course-item">
          <div class="course-image">
            <img src="/static/image/course-cover.jpeg" alt="">
          </div>
          <div class="course-info">
            <h3>Python开发21天入门 <span><img src="/static/image/avatar1.svg" alt="">100人已加入学习</span></h3>
            <p class="teather-info">Alex 金角大王 老男孩Python教学总监 <span>共154课时/更新完成</span></p>
            <ul class="lesson-list">
              <li><span class="lesson-title">01 | 第1节：初识编码</span> <span class="free">免费</span></li>
              <li><span class="lesson-title">01 | 第1节：初识编码初识编码</span> <span class="free">免费</span></li>
              <li><span class="lesson-title">01 | 第1节：初识编码</span> <span class="free">免费</span></li>
              <li><span class="lesson-title">01 | 第1节：初识编码初识编码初识编码初识编码</span> <span class="free">免费</span></li>
            </ul>
            <div class="pay-box">
              <span class="discount-type">限时免费</span>
              <span class="discount-price">￥0.00元</span>
              <span class="original-price">原价：9.00元</span>
              <span class="buy-now">立即购买</span>
            </div>
          </div>
        </div>

      </div>

      <!-- 分页器 -->
      <div class="block course_pagination">
        <el-pagination
          @size-change="handleSizeChange"
          @current-change="handleCurrentChange"
          :current-page.sync="filter.page"
          :page-sizes="[2, 3, 4, 5]"
          :page-size="filter.page_size"
          layout="sizes, prev, pager, next"
          :total="course_total">
        </el-pagination>
      </div>
    </div>
    <Footer></Footer>
  </div>
</template>

<script>
  import Header from "./common/Header"
  import Footer from "./common/Footer"

  export default {
    name: "Course",
    data(){
      return{
        category: 0,
        category_list: [],
        course_list: [],
        filter: {
            course_category: 0,   // watch 检测分类查询的变化
            ordering: "-id",      //  默认排序条件
            page_size: 2,         // 默认每页显示数据量
            page: 1               // 当前页

        },
        course_total: 10
      }
    },
    components:{
      Header,
      Footer,
    },
    created () {
      this.get_category();
      this.get_course();
    },
    watch: {
        "filter.course_category": function(){
            // 当切换分类条件时，因为有些分类没有那么多页的数据，
            // 所以我们需要重置页码，否则后端获取不到数据
            this.filter.page = 1;
            this.get_course();  // 当切换查询条件时，就会发送请求
        },
        "filter.ordering": function () {
            this.get_course();
        },
        "filter.page": function () {
            this.get_course();
        }
    },
    methods: {
        handleSizeChange(val) {
            // console.log(`每页 ${val} 条`);
            this.filter.page_size = val;
        },
        handleCurrentChange(val) {
            // console.log(`当前页: ${val}`);
            this.filter.page = val;
        },

        get_category () {
            this.$axios.get(`${this.$settings.Host}/course/category/`)
                .then(res => {
                    this.category_list = res.data;
                })
                .catch(err => console.log(err))
        },
        get_course () {
            let params = {
                ordering: this.filter.ordering,
                page_size: this.filter.page_size,
                page: this.filter.page
            };

            // 如果分类是0，params为空，则表示不进行筛选，查询全部，则不需要传递任何分类参数
            if (this.filter.course_category > 0) {
                // 一旦 course_category 发生变化，就会触发watch，再次发送请求
                params.course_category = this.filter.course_category;
            }

            this.$axios.get(`${this.$settings.Host}/course/`, {
                params: params
            })
                .then(res => {
                    this.course_list = res.data.results;
                    this.course_total = res.data.count;
                })
                .catch(err => {
                    console.log(err)
                })
        }
    }
  }
</script>

<style scoped >
  .course{
    background: #f6f6f6;
  }
  .course .main{
    width: 1100px;
    margin: 35px auto 0;
  }
  .course .condition{
    margin-bottom: 35px;
    padding: 25px 30px 25px 20px;
    background: #fff;
    border-radius: 4px;
    box-shadow: 0 2px 4px 0 #f0f0f0;
  }
  .course .cate-list{
    border-bottom: 1px solid rgba(51, 51, 51, .05);
    padding-bottom: 18px;
    margin-bottom: 17px;
  }
  .course .cate-list::after{
    content:"";
    display: block;
    clear: both;
  }
  .course .cate-list li{
    float: left;
    font-size: 16px;
    padding: 6px 15px;
    line-height: 16px;
    margin-left: 14px;
    position: relative;
    transition: all .3s ease;
    cursor: pointer;
    color: #4a4a4a;
    /* transparent 透明 只为了选中时出现有颜色的框框，而不会引起抖动 */
    border: 1px solid transparent;
  }
  .course .cate-list .title{
    color: #888;
    margin-left: 0;
    letter-spacing: .36px;
    padding: 0;
    line-height: 28px;
  }
  .course .cate-list .this{
    color: #ffc210;
    border: 1px solid #ffc210!important;
    border-radius: 30px;
  }
  .course .ordering::after{
    content:"";
    display: block;
    clear: both;
  }
  .course .ordering ul{
    float: left;
  }
  .course .ordering ul::after{
    content:"";
    display: block;
    clear: both;
  }
  .course .ordering .condition-result{
    float: right;
    font-size: 14px;
    color: #9b9b9b;
    line-height: 28px;
  }
  .course .ordering ul li{
    float: left;
    padding: 6px 15px;
    line-height: 16px;
    margin-left: 14px;
    position: relative;
    transition: all .3s ease;
    cursor: pointer;
    color: #4a4a4a;
  }
  .course .ordering .title{
    font-size: 16px;
    color: #888;
    letter-spacing: .36px;
    margin-left: 0;
    padding:0;
    line-height: 28px;
  }
  .course .ordering .this{
    color: #ffc210;
  }
  .course .ordering .price{
    position: relative;
  }
  .course .ordering .price::before,
  .course .ordering .price::after{
    cursor: pointer;
    content:"";
    display: block;
    width: 0px;
    height: 0px;
    border: 5px solid transparent;
    position: absolute;
    right: 0;
  }

  .course .ordering .price::before{
    border-bottom: 5px solid #aaa;
    margin-bottom: 2px;
    top: 2px;
  }
  .course .ordering .price::after{
    border-top: 5px solid #aaa;
    bottom: 2px;
  }
  .course .ordering .price_up::before{
    border-bottom-color: #ffc210;
  }
  .course .ordering .price_down::after{
    border-top-color: #ffc210;
  }
  .course .course-item:hover{
    box-shadow: 4px 6px 16px rgba(0,0,0,.5);
  }
  .course .course-item{
    width: 1050px;
    background: #fff;
    padding: 20px 30px 20px 20px;
    margin-bottom: 35px;
    border-radius: 2px;
    cursor: pointer;
    box-shadow: 2px 3px 16px rgba(0,0,0,.1);
    /* css3.0 过渡动画 hover 事件操作 */
    transition: all .2s ease;
  }
  .course .course-item::after{
    content:"";
    display: block;
    clear: both;
  }
  /* 顶级元素 父级元素  当前元素{} */
  .course .course-item .course-image{
    float: left;
    width: 423px;
    height: 210px;
    margin-right: 30px;
  }
  .course .course-item .course-image img{
    width: 100%;
    height: 210px;
  }
  .course .course-item .course-info{
    float: left;
    width: 596px;
  }
  .course-item .course-info h3 {
    font-size: 26px;
    color: #333;
    font-weight: normal;
    margin-bottom: 8px;
  }
  .course-item .course-info h3 span{
    font-size: 14px;
    color: #9b9b9b;
    float: right;
    margin-top: 14px;
  }
  .course-item .course-info h3 span img{
      width: 11px;
      height: auto;
      margin-right: 7px;
  }
  .course-item .course-info .teather-info{
      font-size: 14px;
      color: #9b9b9b;
      margin-bottom: 14px;
      padding-bottom: 14px;
      border-bottom: 1px solid #333;
      border-bottom-color: rgba(51,51,51,.05);
  }
  .course-item .course-info .teather-info span{
      float: right;
  }
  .course-item .lesson-list::after{
      content:"";
      display: block;
      clear: both;
  }
  .course-item .lesson-list li {
    float: left;
    width: 44%;
    font-size: 14px;
    color: #666;
    padding-left: 22px;
    /* background: url("路径") 是否平铺 x轴位置 y轴位置 */
    background: url("/static/image/play-icon-gray.svg") no-repeat left 4px;
    margin-bottom: 15px;
  }
  .course-item .lesson-list li .lesson-title{
      /* 以下3句，文本内容过多，会自动隐藏，并显示省略符号 */
      text-overflow: ellipsis;
      overflow: hidden;
      white-space: nowrap;
      display:inline-block;
      max-width: 200px;
  }
  .course-item .lesson-list li:hover{
      background-image: url("/static/image/play-icon-yellow.svg");
      color: #ffc210;
  }
  .course-item .lesson-list li .free{
      width: 34px;
      height: 20px;
      color: #fd7b4d;
      vertical-align: super;
      margin-left: 10px;
      border: 1px solid #fd7b4d;
      border-radius: 2px;
      text-align: center;
      font-size: 13px;
      white-space: nowrap;
  }
  .course-item .lesson-list li:hover .free{
      color: #ffc210;
      border-color: #ffc210;
  }
  .course-item .pay-box::after{
    content:"";
    display: block;
    clear: both;
  }
  .course-item .pay-box .discount-type{
    padding: 6px 10px;
    font-size: 16px;
    color: #fff;
    text-align: center;
    margin-right: 8px;
    background: #fa6240;
    border: 1px solid #fa6240;
    border-radius: 10px 0 10px 0;
    float: left;
  }
  .course-item .pay-box .discount-price{
    font-size: 24px;
    color: #fa6240;
    float: left;
  }
  .course-item .pay-box .original-price{
    text-decoration: line-through;
    font-size: 14px;
    color: #9b9b9b;
    margin-left: 10px;
    float: left;
    margin-top: 10px;
  }
  .course-item .pay-box .buy-now{
    width: 120px;
    height: 38px;
    background: transparent;
    color: #fa6240;
    font-size: 16px;
    border: 1px solid #fd7b4d;
    border-radius: 3px;
    transition: all .2s ease-in-out;
    float: right;
    text-align: center;
    line-height: 38px;
  }
  .course-item .pay-box .buy-now:hover{
    color: #fff;
    background: #ffc210;
    border: 1px solid #ffc210;
  }
  .course_pagination {
    text-align: center;
    margin-bottom: 60px;
  }
</style>
